Adrian Bejan | City Beltway, from Design in Nature
In this video, Adrian Bejan describes how a city grows from a small village road into a city block and then into a grid, and how the center and the periphery change over time as the population and the diameter increase. He explains that travel across the city becomes slower as the city grows, and he describes a stepwise change in which going around becomes shorter than going through, leading to the appearance of a beltway. He notes that speed on the beltway can increase because there are no traffic lights and because decisions are made by the city government and politicians, leading to an upward trend. He connects this to a threshold moment when people begin “banging on the doors” of decision makers, and he says that later another beltway with a bigger diameter will occur in the same predictable manner. He then links this way of looking at design and movement to earlier developments, moving to boats with sails, the Near East, the Mediterranean, and a Greek ship with oars on three floors that he compares to a gearbox.
Bejan starts from the city block in the smallest and oldest village, describing a dirt road between a few houses that became the city block. He says cities grew from city blocks arranged in a grid and points to places like Paris, Florence, and Rome.
He describes two kinds of cities: an old center of very narrow streets and almost square city blocks, built for carriages, horses, or oxen, and built in stone. He says the old city is not destroyed, while the periphery migrates outward as population increases.
He explains that as the diameter increases, the time it takes to cross the city increases, even at relatively low speeds through the grid. He then describes the beltway as a way to avoid traffic, noting that going around is shorter than going across.
Bejan says the beltway speed can increase over time because there are no traffic lights and because speed is increased by decisions made by the city government and politicians. He connects faster allowable vehicle speed with the earlier arrival of the beltway and says the tendency is tied to facilitating movement and life.
He shifts to boats with sails and a story about the Near East and the Mediterranean, naming Lebanon, Israel, Iberia, the Phoenicians, Tunisia, Carthage, and the Greeks. He describes the Triim, with convicts pulling oars on three decks, and says this is the design of the gearbox, adding notes on Greek and Latin words.
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